A change in any factor other than the wage will cause a shift of the supply curve for labour. These are things such as changes in preferences and social norms, changes in population, changes in wealth and changes in working conditions.
If, for instance, there is an increase in the number of workers for an occupation due to an increase of new entrants into the labour market, the supply of labour for this occupation will increase. In terms of the market supply curve of labour, this is indicated by a rightward shift of the market supply curve from S1 to S2 as indicated in the following diagram: